Vented movable resistor contact for air blast circuit breakers



Aug. 3, 1965 H. FORWALD 3,198,916

VENTED MOVABLE RESISTOR CONTACT FOR AIR BLAST CIRCUIT BREAKERS Filed Nov. 29, 1962 I II I II I III United States Patent O 3,198,916 VENTED MOVABLE RESISTOR CONTACT FOR ARR BLAST CIRCUIT BREAKERS Haakon Forwaid, Ludvika, Sweden, assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of llennsylvania Filed Nov. 29, 1962, Ser. No. 240,883 3 Claims. (Cl. 200148) This invention relates to air blast circuit breakers, and more specifically relates to a novel construction for the auxiliary movable contact of an air blast circuit breaker which is connected in series with a resistor wherein the auxiliary contact and resistor are connected in parallel with the main breaking gap.

More specifically, and in accordance with the invention, the auxiliary movable contact is provided with a nozzle-shaped channel therethrough through which a strong flow of air may pass during interruption with the movable contact being carried by a piston which moves responsive to the operation of the main breaking gap of the circuit breaker.

Accordingly, a primary object of this invention is to provide a novel auxiliary breaking gap for air blast circuit breakers.

Another object of this invention is to improve the operating characteristics of air blast circuit breakers having interrupter resistors associated therewith.

Another object of this invention is to provide a novel nozzle-shaped outflow channel in the movable contact of the auxiliary breaking gap of an air blast circuit breaker.

A further object of this invention is to insure effective interruption of the auxiliary breaking gap of an air blast circuit breaker.

These and other objects of this invention will become apparent from the following description when taken in connection with the drawing which shows an embodiment of an air blast circuit breaker constructed in accordance with the invention.

Referring now to the figure, the circuit breaker interrupter includes a conductive container 1 which is permanently filled with sufficient compressed air for at least one operation, and which contains a main breaking gap and an auxiliary breaking gap. The main breaking gap is comprised of a stationary contact 2 and a movable cooperating contact 3 which is provided with the usual central channel (not shown) through which air may move during the time that the movable contact 3 is moved from the engaged position shown to a disengaged position.

The container 1 is further provided with a conductive dome 4 in a wall thereof which receives resistor 5 which is connected in parallel with the main contacts 2 and 3, as will be described more fully hereinafter.

The upper end of resistor 5 is mechanically and electrically secured to the top of dome 4, and, thus, is at the potential of conductive container 1. The lower end of resistor 5 carries auxiliary stationary contact 6 of the auxiliary breaking gap which further includes the movable auxiliary contact 7. The movable auxiliary contact 7 is provided with a nozzle-shaped outflow channel 8 therethrough, and the movable contact 7 is carried by a piston 9 which forms the movable element of a blocking valve.

Piston 9 is carried in a cylinder 10 which is directly secured to the stationary contact 2 of the main breaking gap.

A spring 11 is captured beneath piston 9 to thereby bias nozzle-shaped auxiliary movable contact 7 toward engagement with auxiliary stationary contact 6. Piston 9 divides cylinder 10 into two volumes; upper volume 12 and lower volume 13. The upper volume 12 is in permanent communication with the interior of container 3,198,916 Patented Aug. 3, 1965 1 by virtue of permanently open orifices in the top of cylinder 10. The lower volume 13 is connectable to open air through a channel 14 or to a by-pass connecting channel 15 and thence to the interior of container 1.

When the auxiliary breaking gap is in its open position, piston 9 closes communication channel 14 where, if desired, the bottom of piston 9 may have appropriate gasketing material for sealing off the ends of channel 14.

The stationary contact 2, along with the movable auxiliary breaking contact 7, are each supported by leadthrough bushing 16 which passes through the wall of container 1. The channels 14 and 15 described above are machined into the central conductor of lead-through bushing 16.

A switching valve 17 is then placed at the outer end of the lead-through bushing conductor, and is movable to either close off by-pass connecting channel 15 when valve 17 is moved upwardly, or to connect channel 15 to channel 14 when it is in the position shown.

When channels 14 and 15 are connected, as illustrated in the drawing, compressed air will be supplied from the interior of container 1 to channel '15, and thence to channel 14 to retain auxiliary movable contact 7 in the position shown.

The switching valve 17 is provided with an independent operating mechanism, and is normally held in the position shown by means of compression spring 18 which biases piston 19 downwardly in its cylinder 20. The valve 17 is connected to piston 19 so that it is normally held in the position shown.

The bottom of cylinder 20 is then connected to a compressed air conduit 21 to a main compressed air operating conduit 22 through which compressed air is supplied to the mechanism housing 23 of movable contact 3 in the usual manner.

The air blast circuit breaker which is shown in the closed position may be opened when compressed air is connected to conduit 22. That is to say, the application of compressed air to the operating mechanism 23 will cause the withdrawal of movable contact 3 from its engaged position with stationary contact 2. At the same time, conduit 21 is placed under pressure, whereby piston 19 is moved upwardly so that valve head 17 closes off the end of channel 15.

At the same time, channel 14 is connected to open air through the vent normally sealed by valve 17, whereby the high pressure air in volume 13 under piston 9 is exhausted so that the compressed air in volume 12 can force piston 9 downwardly. The auxiliary breaking gap is thereby opened so that compressed air may now flow through the nozzle-shaped channel 8 in auxiliary movable contact 7 and out to open air; the flow of blast air aiding in the extinction of any are which exists between contacts 6 and 7.

Once the piston 9 reaches its lowest position, it closes communicating channel 14 so that the flow of extinguishing air through channel 8 is stopped to thereby conserve the pressurized air within container 1.

In order to close the air blast circuit breaker of the drawing, it is only necessary to remove compressed air from conduit 22. This will cause contact 3 to move to the left and to its engaged position in the usual manner, while at the same time, the emptying of air from conduit 21 will permit spring 18 to move valve 17 back to the position shown in the drawing. This permits the high pressure air in container 1 to communicate with channel 14 through channel 15 so that the piston 9 is moved upwardly to move contact 7 into engagement with stationary contact 6.

The relative times in operation of the main breaking gap and auxiliary breaking gap can, of course, be delayed or adjusted with respect to one another by arranging appropriate throttle valve means in conduit 21.

It has been learned that the nozzle-shaped outflow channel 8 in auxiliary movable contact 7 should have a moderate area in relation to the area of the channels which connect the space 13 to open air so that the contact 7 can be quickly moved toward an open position during the opening operation.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferredftherefore, that the scope of this invention be limited not by the specific disclosure herein but only by the appended claims.

What is claimed is:

1. An air blast circuit breaker comprising a conductive container permanently filled with air, insulator support means connected to and supporting said conductive container; said container having first and second main cooperating contacts therein; a bushing insulator having a central conductor extending therethrough; said bushing insulator extending through said container; said first main contact being connected to the end of said central conductor; said second contact being electrically connected to said container; a resistor disposed in said container having a first and second end; said first end of said resistor connected to said container; a first and second auxiliary cooperating contact; said first auxiliary contact comprising a stationary contact secured to said second end of said resistor in insulated relation with respect to said container; said second auxiliary contact including a stationary portion and a movable portion carried by said stationary portion; said stationary portion of said second auxiliary contact being mechanically and electrically connected to said end of said central conductor; said second auxiliary contact being movable with respect to said first auxiliary contact; said second auxiliary contact having an orifice extending therethrough; said orifice being connectable to open air when said second auxiliary contact moves to a disengaged position with respect to said first auxiliary contact: said central conductor having a channel therein connectable to open air; and a blocking valve for said channel; said channel in said central conductor communicating with said orifice in said second auxiliary contact when said blocking valve is opened; said second auxiliary contact being carried on said blocking valve.

2. The device substantially as set forth in claim 1 which includes a bypass channel for connecting said blocking valve to the pressure within said container; said by-pass channel being opened simultaneously with the closing of said first and second main contacts and being closed simultaneously with the opening of said first and second main contacts.

3. The device substantially as set forth in claim 2 wherein said by-pass channel is contained in said central conductor.

References Cited by the Examiner UNITED STATES PATENTS 2,964,605 12/60 Schulz 200-148 3,018,352 1/62 Schulz 200--148 3,093,717 6/63 Forwald 200148 3,108,168 =10/63 Forwald 200-148 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

1. AN AIR BLAST CIRCUIT BEAKER COMPRISING A CONDUCTIVE CONTAINER PERMANENTLY FILLED WITH AIR, INSULATOR SUPPORT MEANS CONNECTED TO AN SUPPORTING SAID CONDUCTIVE CONTAINER; SAID CONTAINER HAVING FIRST AND SECOND MAIN COOPERATING CONTACTS THEREIN; A BUSHING INSULATOR HAVING A CENTRAL CONDUCTOR EXTENDING THERETHROUGH; SAID BUSHING INSULATOR EXTENDING THROUGH SAID CONTAINER; SAID FIRST MAIN CONTACT BEING CONNECTED TO THE END OF SAID CENTRAL CONDUCTOR; SAID SECOND CONTACT BEING ELECTRICALLY CONNECTED TO SAID CONTAINER; A RESISTOR DISPOSED IN SAID CONTAINER HAVING A FIRST AND SECOND END; SAID FIRST END OF SAID RESISTOR CONNECTED TO SAID CONTAINER; A FIRST AND SECOND AUXILIARY COOPERATING CONTACT; SAID FIRST AUXILIARY CONTACT COMPRISING A STATIONARY CONTACT SECURED TO SAID SECOND END OF SAID RESISTOR IN INSULATED RELATION WITH RESPECT TO SAID CONTAINER; SAID SECOND AUXILIARY CONTACT INCLUDING A STATIONARY PORTION AND A MOVABLE PORTION CARRIED BY SAID STATIONARY PORTION; SAID STATIONARY PORTION OF SAID SECOND AUXILIARY CONTACT BEING MECHANICALLY AND ELECTRICALLY CONNECTED TO SAID END OF SAID CENTRAL CONDUCTOR; SAID SECOND AUXILIARY CONTACT BEING MOVABLE WITH RESPECT TO SAID FIRST AUXILIARY CONTACT; AND SECOND AUXILIARY CONTACT HAVING AN ORFICICE EXTENDING THERETHROUGH: SAID ORIFICE BEING CONNECTABLE TO OPEN AIR WHEN SAID SECOND AUXILIARY CONTACT MOVES TO A DISENGAGED POSITION WITH RESPECT TO SAID FIRST AUXILIARY CONTACT: SAID CENTRAL CONDUCTOR HAVING A CHANNEL THHEREIN CONNECTABLE TO OPEN AIR; AND A BLOCKING VALVE FOR SAID CHANNEL; SAID CHANNEL IN SAID CENTRAL CONDUCTOR COMMUNICATING WITH SAID ORIFICE IN SAID SECOND AUXILIARY CONTACT WHEN SAID BLOCKING VALUE IS OPENED; SAID SECOND AUXILIARY CONTACT BEING CARRIED ON SAID BLOCKING VALVE. 